Molten metal pump



March 8,1933- F. LANNERT MOLTEN- METAL PUMP Filed April 29, 1936 NSS" wenz/0f Fran/z L azzfz Patented Mar'.

UNITED STATES PATENT OFFICE MOLTEN METAL PUMP poration of Illinois Application April 29, 1936, Serial No. 76,899

9 Claims.

This invention relates to pumps such as are used in die-casting machines to force molten metal into the die. It is, of course, desirable that there be no leakage or wash between the Vplunger and cylinder, as such leakage makes it diiiicult or impossible to force the molten metal into the die under the desired degree of pressure with certainty and uniformity. Moreover, such wash causes erosion of the plunger. and cylinder, which becomes progressively worse as the clearance between the plunger and the cylinder increases.

Heretofore the plunger has been of solid construction and of such diameter in the beginning as to have a snug working fit in the cylinder. It has, however, been impossible to prevent seepage of the molten metal past the plunger, with consequent erosion, so that the useful life of the v plunger has been relatively short and it has been necessary to bore out the cylinder at relatively frequent intervals.. Furthermore, inasmuch as the plunger is immersed in the molten metal, it has been necessary for the workman to disconnect and withdraw the plunger upon shutting down 25 the machine at noon and night, and to replace the plunger upon resuming operation of the machine, for the reason that if the plunger were left at rest in the molten metal, there would be danger that the plunger would stick to the cylinder, particularly if the heat became excessive through failure or misoperation of the thermostatic control usually provided.

The object of the present invention is to overcome the objections and disadvantages arising in connection with the use of the types of plungers heretofore employed. This object I have attained by providing a plunger comprising a body having ample clearance between it and the cylinder wall, which body carries a plurality of ring segments which are arranged to be forced into proper working contact with the cylinder wall by the pressure on the molten metal in the injection stroke, the segments. being so arranged with relation to one another as to prevent seepage or wash of the molten metal past the plunger.

In the accompanying drawing, which illustrates several of the various possible embodiments of my invention,

Figure 1 is a sectional View of a molten metal pump provided with a plunger embodying the features of the invention.

Fig. 2 is. an axial sectional view of the plunger shown in Fig. 1 upon an enlarged scale.

Fig. 3 is a View similar to that of Fig. 2, but showing the plunger in engagement with the cylinder wall, as occurs during the injection stroke.

Figs. 4, 5 and 6 are transverse sectional views taken in the planes of lines 4-4, 5--5 and 6 6, respectively, of Fig. 2.

Fig. 7 is a view similar to that of Fig. 2 but showing an alternative construction.

Fig. 8 is a section on line 8-8 of Fig. 7.

Fig. 9 is a view similar to that of Fig.,2, but showing an alternative construction, which at present is the preferred form.

The plunger construction herein disclosed is not limited to use' with a pump of the character shown in Fig. 1, but, on vthe contrary, it may be used in molten metal pumps of various constructions. Fig. 1 will, however, serve to impart an understanding of the practical conditions under which the improved plunger is used. In this View, l is a melting pot containing molten metal a. In the pot I is a pump cylinder 2. A port 3 in the cylinder permits molten metal to flow from the melting pot I into the pump cylinder. The lower end of the pump cylinder communicates with a discharge passage 4 that leads to the die (not shown).

The plunger comprises a body 5, herein shown as cylindrical. The body may be connected in any desired way to a means for reciprocating the plunger. Ample clearance is provided between the body 5 and the cylinder wall, as shown in Fig. 3, so as to obviate any danger that the body shall stick to the cylinder. In the lower end of the body 5 is' an axial screw-threaded opening 6 into which is screwed a stud 'I. The stud 'I has. an annular shoulder 8 that stops against a similar shoulder on the body 5. On the lower end of the stud I is a head or flange 9.

On the stud 'I is a ring I Il adapted to rest upon the head 9, said ring being herein shown as of the same external diameter as the body 5. Between the ring IIJ and the lower end of the body 5 is a set of concentric ring segments arranged to formvtwo .inner rings. and two outer rings. The lower inner ring consists of segments I I, I2 and I3 (Fig. 6). The upper inner ring consists of segments I4, I5 and I6, Fig. 5). Surrounding these rings is a lower outer ring formed of the segments Il, I8 and I9 (Figs. 5 and 6), and an upper outer ring composed of the segments 2G, 2I and 22 (Fig. 4). The ring segments are preferably hardened and ground. The outer rings are in contact with each other; and the inner rings are in contact with each other.

The upper side of the ring I 0 is beveled and the lower edges of the ring segments Il, I2, I3,

I1, I8 andH I9 are correspondingly beveled for contact with the ring I8. Similarly, the'lower end of the body 5 is beveled and the'upper ends of the segments I4, I5, IB, 20, 2| and 22 are beveled to make contact with the body 5. It will be seen that pressure of the ring I against the .molten metal in theV cylinder 2 will spread the ring segments radially outward so as to force the segments I-1, I8, I9, 28, 2|, and 22 into contact with the cylinder Wall and also force the segments II,

' I2, I3, I4, I5 and I6 outwardly into contact with the segments I1, I8, I9, 20, 2I and 22.

As shown in Figs. 2, 4, and 6, there is sumcient clearance between the stud 1 and the inner rings so as to produce an annular space 23,iwhereby the rings may be placed undeninternal pressure of molten metal, as will'now be explained.

The expansion of the ring segments into con-V tact with the cylinder wall under the pressure of the ring I0 provides a space 23a (Fig. 3) between.

theA head 9 and the ringnIU, into which molten metal may flow; The diameter ofthe central opening231? (Fig. 3) of the ringv I0 is sufliciently greater thanthe diameter of the stud 1 so that the molten metal entering the space 23a between thevhead 9 and the ring II) may ilow up into the space 23b and thence into the space 23jbetween the stud 1 and the' inner ring segments II, I2, I3, I4, I5 andlr I6 to` force or assist in forcing the ring segments outwardly against the cylinder.

-When the rings are expanded into contact .with

V the cylinder, .thereis a slight clearance or space between adjacent ends ofthe ring segments, but

it will be -noted that these spaces are' staggered I; so as to limit the extent to which molten metal may ilcw up. Thus, considering, Figs. `3 and 6,

molten metal between the periphery ofthe ring lllandgthe cylinder wall can flowup into the spacesbetween thevends of the segments- ,I 1, I8

and I9.,A but cannot flow any higher because the 7fsegments,20,-2Iand 22 (Figs. 3 and 4) are oftset orstaggered with relation to the segments I1, I8 and \!9;sothat the segment 28 closes the up'- perend of the space betweenthe adjacent ends of the segments I9 and I1, the segment 2I closes the upper end of the space between. the adjacent endsof the segments-l1 andV I8, and the segment 22 closes-the upper end of the spacebetween the adjacent-,ends ofthe-'segments I8 and I9.

Molten metal-entering the annular space23.` (Fig. 6) betweenfthe' stud y1 and the inner rings may enter the spaces'between the Vadjacent `ends of the segments II,- r-I21and I3, but cannot flow anyy farther radiallyl outwardly because such spaces are closed by the segments I1, I 8 and I9i. lThe upper ends ofthe spaces between adjacent ends "of the vsegments II,` I2 vand I3 are closed by the-segments I4, I5 and I6. Similarly, molten metal entering the spaces between-'the adjacent'er'nisY of the segments I4, I5 and I6 can flow no farther, because said spaces areV closed by` the segments 20, 2| and 22 and by` the beveledsurface ofthe body 5.

Inzorder tomaintain thering segments in staggered relation to one another, they are connected by dowel pins 25. One of these pins (see Fig. 6) holds the `segments I3 and I8 in staggeredrelation, another pin (Fig. 5) holds the. segments I8 and I6 in staggered relation, and the other pin (Fig. 4) holds the segments 22 and I6 in stag- 'gered relation,`allof the segments being `thereby maintained in proper location with reference to one' another. lEach pinrnay be xedin one segment and loose in thefother segment.

rtwiil be `noted that the outer ring; formed ofc.

the segments I1, I8 (and I9 is higher than the inner ring formed of the segments II, I2 and I3, thereby producing `a broken joint between the two outer rings and the two inner rings.

The described arrangement of ring segments produces during the injection stroke a suiliciently tight contact between the plunger and the cylinder so as to prevent the escape of molten metal past the plunger, thereby preventing erosive wash and lossl of pressure.

While the spaces `23EL andL 23b provide a pasi sage for the molten metal to reach the space 23,

`Iprefer to use anotherarrangement which provides a freer or more direct passage. This is shown in Figs. '1 and 8. An axial duct 26 is formed in the studf1, said duct opening upon the lower endk of the stud. The upper end o! the duct communicates with a transverse duct '21, which extends to the periphery of the stud so as to allow the molten metal to exert pressure upon the inner sides o f the ring segments IL'IZ, I3., I4, I5 and I6.

In the,forms4 of plungershown in Figs. 1 to 8', thel area of the ring I8 which is initially ex- V posed tothe pressure of the .m'oltenmetal is that beyond Ythe periphery of the head 9. In Fig. 9.

I have shown a construction wherein the entire,

surface of the lower end of the plunger is exposed to thek pressure of the molten metal for Onthelower end of the-stud 29 is a circular head 32I which is of. thesame diameter as they The upper side of the head 32 and the b ody 5a. lower ,end of the body 5a are. bevelled, as in the case ofthe body 5 and ring I8, and between the head `32V andthe body 5a is located a Set of ring segments identical with the ring segmets previously described.

In assembling the plunger shown in Fig. 9, the stud 29.is inserted into the bore 28-28 until its upper end projects above the body 5a. split ring 3l is then placed in the groove 38 and the stud29 drawn downwardly to place the ring 3l within'the bore 28a. The ring segments are then assembled in the space between` the body 5a and the head 3,2.

All of the forms of plungers herein illustrated are adapted to provide proper contact between the plunger andthe, cylinder so as to prevent the escape of metal-pastthe plunger in the injection stroke. Asshown in Figs. 1 and 3, there is ample clearance between'the body 5 and the ring I0 (or `the body Y5a and the head 32) and the` cylinder wall. Although they ring segments are at all times immersed in the molten metal, experience. has shown that the plunger need not be The withdrawn from' the cylinder when the machine is shut down, as the body of the plunger and the ring I0 orthe head32r do not stick to the cylinder.

By means of my invention, the efficiency Vof the plunger in operation is increasedLthe useful life of the plunger and the cylinder is substantially' prolonged, and the necessity `of disconnecting and withdrawing the plunger upon shutting down the machine and replacing and connecting the plunger lwhen the machine is again koperated is obviated.

While I have illustrated and described various details, it will be understood that the invention is not limited thereto, the scope of the invention being indicated in the appended claims.

In certain of the claims which relate more particularly to the segmental rings, I have referred to the body 5, stud l and ring Ill as a structure having an annular space in which an expansive ring or rings are located. As applied to the form shown in Fig. 9, the structure that supports the expansive ring or rings consists of the body 5iL and the stud 29.

I claim as my invention:

1. In a molten metal pump of the cylinder and plunger type, said plunger comprising a body of sufficiently smaller diameter than the cylinder so as to be out of contact therewith, a stud axially alined with the body and connected thereto for limited longitudinal movement andy projecting from one end of the body, the projecting end of said stud having a head of suiiiciently smaller diameter than the cylinder so as to be out of contact therewith, the side of said head which faces the body and the end of said body which faces said head being beveled, and a series of correspondingly beveled ring segments extending around said stud between said beveled surfaces and arranged to be forced by the wedging action of said beveled surfaces into contact with the cylinder on the pumping stroke of the pump.

2. In a molten metal pump of the cylinder and plunger type, said plunger comprising a body, a stud axially alined with the body and connected thereto for limited longitudinal movement and projecting from one end of the body, the projecting end of said stud having a head, the side of said head which faces the body and the end of said body which faces said head being beveled, and correspondingly beveled ring segments located between said beveled surfaces and arranged on the pumping stroke to be forced outwardly by the wedging action of said beveled surfaces into contact with the cylinder.

3. In a molten metal pump of the cylinder and plunger type, said plunger comprising a body, a stud axially alined with the body and connected thereto for limited longitudinal movement and projecting from one end of the body, the projecting end of said stud having a head which is exposed to the pressure of the molten metal, and ring segments located between said head and the end of the body and encircling the stud, and arranged to be forced outwardly into contact with the cylinder, said head having a passage leading to the surface of that portion of the stud which is encircled by the ring segments, whereby molten metal may flow into contact with the concave side of the ring segments.

4. In a molten metal pump of the cylinder and plunger type, said plunger comprising a body, a stud connected thereto for limited longitudinal movement and projecting from one end of the body, the projecting end of said stud having a head, and ring segments encircling the stud and located between said head and the end of the body and arranged to be forced outwardly into contact with the cylinder, said stud having a passage opening upon said head and extending to the space between said head and the body to expose said segments to pressure of the molten metal internally of the segments.

5. In a molten-metal pump of the cylinder a stud secured to 'and projecting. axially from one end. of the body, the outer end of said stud having a head of less diameter than the body, a. ring slidably mounted on the stud alongside the head. and' of larger diameter than the head, the sidejof said .ring which faces the body andthe end of said body which faces the ring being beveled, and correspondingly beveled ring segments located between said beveled surfaces and arranged to be forced outwardly by the Wedging action of said surfaces into contact with the cylinder.

6. In a moltenmetal pump of the cylinder and plunger type, said plunger comprising a body, a stud rigidly secured to and projecting axially from one end of the body, the outer end of said stud having a head, a ring slidably mounted on the stud alongside the head and of larger diameter than the head, the side of said ring which faces the body and the end of said body which faces the ring being beveled, and correspondingly beveled ring segments located between said beveled surfaces and arranged to be forced outwardly into contact with the cylinder, the other side of said ring being exposed to the Ipressure of the molten metal to force said ring away from thehead toprovide space for the entrance of molten metal, there being clearance between the ring segments and the stud, which clearance is in communication with said space to Vpermit the molten metal to exert pressure against the concave sides of the ring segments.

7. A molten-metal pump of the cylinder and plunger type, said plunger comprising a structure having an annular space between its ends, and a y'plurality of rings in said space, there being a plurality of outer rings adapted to engage the cylinder wall and a plurality of rings within the outer rings, each of said rings comprisingl a plurality of segments, the joints of one outer ring being staggered with relation to the joints of the other outer ring, the joints of one inner ring being staggered with relation to the joints of the other inner ring, the joint between the outer rings being staggered with relation to the joint between the inner rings, said structure having a passage opening upon the pressure end thereof and extending to said annular space to place said rings under pressure of the molten metal.

8. In a molten-metal pump of the cylinder and plunger type, said plunger comprising a structure having an annular space between its ends, and a plurality of rings in said space, there being a plurality of outer rings in contact with each other vand adapted to engage the cylinder wall and a plurality of rings in contact with each other and located within the outer rings, each of said rings comprising a plurality of segments, the joints of one outer ring being staggered with relation to the joints of the adjacent outer ring, the joints of one inner ring being staggered with relation to the joints of the adjacent inner ring, the line of contact between the outer rings being staggered with relation to the line of contact between the inner rings, said structure having means to place said rings under internal pressure of the molten metal.

`9. In a molten-metal pump of the cylinder and plunger type, said plunger comprising a structure having an annular space between its ends, and a plurality of rings in said space, there being a plurality of outer rings adapted to engage the cylinder wall and a plurality of rings within the outer rings, each of said rings comprising aplurality of segments; ythegjoints f one connecting one segment of each inner ring to th outer ring being staggered with relation to lthe adjacent segment of the corresponding outer ringi Joints ofthe other outer ring, the ijoi'ntsof one andA a dowel pin connecting adjacent segments inner ring being staggered with relation to the of Vtheir. overlapping inner and outer rings to joints of the other inner ring,` the joint between malintain aliy of saidA joints in such staggered 5 the outer rings being'staggeredrelative to'the re1ation.' f

j jomtbetween the inner rings,V and eowl pim;l n, FRANKLANNERT. 

